1. Field of the Invention
The present invention relates to a radiating spacer which has high flexibility and which, when incorporated in an electronic equipment, reduces a load to a heat-generating element, a heat sink employing such a spacer, a radiating spacer part material, an electronic equipment, and a silicone composition.
2. Description of the Background
A heat-generating electronic part such as a transistor or a thyristor generates a heat during its use, and it is important to remove such heat. Heretofore, as a method for removing the generated heat, it has been common to remove the heat by attaching the heat-generating electronic part to a radiating fin or a metal plate with an electrically insulating heat conductive sheet interposed therebetween. As such a heat conductive sheet, a radiation sheet having a heat conductive filler loaded to silicone rubber has been mainly employed.
On the other hand, along with recent high densification of electronic equipments, a system of conducting the heat generated from a heat-generating electronic part directly to a casing of the electronic equipment, may be employed in a case where no space for attaching a radiating fin or the like is available or in a case where an electronic equipment is sealed in so that heat dissipation from the radiating fin located inside to the exterior, is difficult. To carry out such heat conduction, a highly flexible radiating spacer may be employed which has a thickness to fill out the space between the heat-generating electronic part and the casing.
Further, a highly flexible radiating spacer may also be employed between a printed board and a radiating fin for heat dissipation in a case where IC or LSI heat-generating electronic part is mounted on the printed board.
However, conventional radiating sheets commonly employed, are hard with a Shore hardness of at least 90 and accordingly poor in the shape-trailing property. Accordingly, there has been a problem that when such a radiating sheet is pressed against a heat-generating electronic part for close contact, the heat-generating electronic part which is weak against stress is likely to break.
Therefore, a radiating spacer more flexible than a radiating sheet has been developed. However, even then, in a case where the heat-generating electronic part to be contacted with the radiating spacer, is extremely weak against stress, the heat-generating electronic part is likely to break when the radiating spacer is brought in close contact therewith and a load is exerted thereto. Thus, a problem of breakage has not yet been solved.
Along with high densification of electronic equipments, the shape-trailing property has been required more than ever, and a radiating spacer having higher flexibility has now been desired. However, if the material for a radiating spacer is designed to meet such requirement, its surface usually tends to have high adhesiveness. This adhesiveness not only impairs the operation efficiency but also causes deterioration of the thermal conductivity due to adhesion of dust from the atmosphere on the surface of the material, although it may be effective for temporal tacking of the material itself.